A
homopolar motor is a direct current
electric motor with two magnetic poles, the conductors of which always cut unidirectional lines of
magnetic flux by rotating a conductor around a
fixed axis so that the conductor is at right angles to a static
magnetic field. The resulting
EMF (Electromotive Force) being continuous in one direction, the homopolar motor needs no
commutator but still requires
slip rings. The name
homopolar indicates that the
electrical polarity of the conductor and the magnetic field poles do not change (i.e., that it does not require commutation).